A number of different multimedia coding techniques and standards have been established for coding digital multimedia sequences. Many current techniques make use of block-based coding. In block-based coding, frames of a multimedia sequence are divided into discrete blocks of data, and the blocks are coded based on the differences with other blocks.
Motion-based block coding techniques make use of motion vectors to code the blocks of multimedia frames based on motion relative to pixels within blocks of other frames in the multimedia sequence. The motion vectors identify blocks of different frames that were used to code the current multimedia block. By using such motion vectors, the information needed to convey multimedia sequences can be reduced by sending difference information indicative of the differences between the current block being coded and the predictive block identified by the motion vector.
Some spatial-based coding techniques also rely on block coding techniques. In particular, spatial-based coding may use blocks within a given frame to predict a respective block being coded. In addition, discrete cosine transform (DCT) techniques typically operate on blocks of pixels. DCT techniques are often used for image and video compression, and may be used alone or in conjunction with other block-based coding techniques.
Wavelet transform coding is one viable alternative to block-based coding techniques, such as DCT techniques. Wavelet transform coding is sometimes referred to as Discrete Wavelet Transform (DWT). Video or image multimedia compression using wavelet transform coding can eliminate blockiness artifacts (sometimes referred to as tiling), which are commonly exhibited with DCT coding. Moreover, wavelet-based multimedia compression often outperforms block-based DCT compression, particularly when evaluated using the Peak Signal to Noise Ratio (PSNR) or Mean Squared Error (MSE) metrics. Furthermore, the subjective quality of multimedia frames or images compressed with wavelet-based coding may appear better than block DCT methods for the same compression ratio.